The invention relates to a mobile concrete pump with a chassis, a concrete distributing boom rotatable about a vertical axis, arranged on a boom support, as well as with front support legs and rear support legs.
Mobile concrete pumps as described above are used on construction sites for distributing concrete from a central location over a wide area so that, in a pouring process with continuous concrete supply by means of concrete mixers, large concrete slabs can be produced. Furthermore mobile concrete pumps offer the possibility of transporting concrete to high-lying work levels with little effort, a purpose for which in practice mobile concrete pumps whose distributing boom surpasses a height of 60 m have already been used. At such dimensions it is obvious that the stability of the mobile concrete pump presents a problem. In order to insure under all operational conditions a stable platform for the mobile concrete pump with the desired extension of the distributing boom, the front and rear support legs are arranged on the chassis and customarily at the corners of the chassis. However this means that the entire chassis is exposed to the full impact of the distributing boom force and therefore has to be manufactured to be correspondingly stable. For this reason the leg locations were changed by moving the pivot bearings for the front and rear support legs away from the chassis corners and to bring them closer, so that the pivot bearing for the rear support legs is located close to the rear axle of the chassis. It has been found that with the increasing closeness of the pivot bearings to one another torsion problems arise. Furthermore the pivot bearings of the front and rear support legs are arranged relatively far to the rear of the chassis, which requires that the front support legs be extendable very far towards the front so that they are designed to be telescopic. Finally the boom support also projects very far forward on the chassis. As a result of the telescopic support legs and the projecting boom support the flexibility of the mobile concrete pump increased, where actually stability is necessary and desired.
It is desired to spread the front and rear support legs as far away as possible from the chassis to provide a secure stand. However the front and rear support legs in their rest position have to be lodged on the pump in order to move it. Therefore, in order to be able to lodge a sufficient length of the front and rear support legs on the chassis, it has already been proposed to let the front support legs extend rearwardly and the rear support legs forwardly for storage, thereby making use of the length offered by the chassis. However this requires sufficient available space at the construction site so that the front and rear support legs can be deployed from their rest position to their work position in a circular motion passing over an apex. Furthermore in some mobile concrete pumps the support legs are telescopic so that in the rest position only little space is required, while a wide range is available in the work position. The telescopes can impair the stability, aggravating by the increasing number of telescope segment.
It is the object of the invention to provide a mobile concrete pump of the aforementioned kind so that expensive reinforcement of the chassis for avoiding torsion between the pivot bearings of the front and rear support legs can be eliminated, and so that the front and rear support legs in long construction style can be lodged on the chassis without large space requirements during the transfer from the rest position to the work position.
According to the invention, this object is achieved in a mobile concrete pump of the aforementioned kind in that each front support leg and rear support leg arranged on the same side of the chassis have a common swivel axis.
This offers the advantage that only the area directly between the boom support and the pivot axis need be of a particularly stable construction, since the forces from the concrete distributing boom are channeled directly via the boom support and this intermediate area to the support legs, so that the rest of the chassis is not under load. The arrangement of the pivot bearings on a common pivot axis offers an additional space advantage, because the support legs can be made longer in the longitudinal direction of the chassis, since it is no longer necessary to provide a specimens between the swing bearings.
Advantageously the front support legs and the rear support legs are supported on the boom support. During operation while pumping, the concrete distributing boom with boom support and the front and rear support legs can be considered as a self-sufficient unit, which solely for the desired mobility is arranged on the chassis, which in itself does not have to be reinforced, so that cost advantages result for the manufacturer, and furthermore the low inherent weight allows for greater load. With regard to sufficient space availability for a stable support it is advantageous when a base plate is assigned to the boom support, on which the front support legs and rear support legs are lodged.
Within the framework of the invention it is further provided that the front support leg and the rear support leg on the same side are pivotally supported on a bolt arranged coaxially to the pivot axis. The bolt forming a common pivot bearing for the front and rear support legs is fastened in a simple manner by means of a mounting.
A somewhat more complicated mounting is required when the front support leg and the rear support leg on the same side are pivotally supported on separate bolts coaxial with the pivot axis. However this offers the advantage that torsion and bending forces acting on the bolt simultaneously from the front support leg and the rear support leg are avoided.
Each front support leg can be formed by a tubular guide rotatable about the pivot axis, wherein a slide tube present in the support base of the front support leg and traversing the tubular guide is slidably supported in its rest position. This embodiment offers the advantage that the front support leg in its rest position can be positioned on the chassis so that it does not project into the wheel boxes, which have to be kept clear for the wheels. Compared to a construction based exclusively on telescopic means, the support leg has the advantage that the segment connected to the swing bearing does not limit the base length which is formed because of the distance between the clear space reserved for the support leg on the chassis and the pivot bearing. The frequently practiced move to place the swing bearings further rearward, in order to create a sufficient base length, and in this way to accept a shortening of the rear support legs, as well as an indispensable reinforcement of the chassis, is no longer necessary.
Of course it is possible, in order to increase the range of the front support legs, to design the slide tube as a telescope, this way also making use of the inherent advantages, whereby the first segment of the telescope can use the entire length of the slide tube.
In order to support the front leg on the chassis in the most compact manner it is advantageous for the chassis to have a recess, into which the rear end of the slide tube can project. The part of the slide tube rearwardly projecting beyond the pivot axis can enter this recess and can be swung and guided past the construction elements located on the chassis, in order to slide the slide tube into the tubular guide.
In alternative embodiment the rear support leg has a recess into which the slide tube projects in its rest position, and thus way the rear support leg can be thicker and more rigid without increasing the cumulative dimension of the rear and front support legs.
Suitably in this embodiment the rear support leg has two mounting plates by means of which it is connected to the bolt and between which the front support leg is coupled with the bolt. In the rear support leg can be left free between the mounting plates so that the pivot angle of the tubular guide is not impaired.
The concrete distributing boom with the boom support is mounted directly on the chassis close to the front axle, which increases the rigidity and improves stability due to the lack of intermediate members.